DESCRIPTION: This is an application by Victor Nizet, M.D. for a KO8 award for mentored studies under the direction of Craig Rubens, M.D., in the Department of Pediatrics, Washington University and the Children's Hospital and Medical Center, Seattle, WA. Dr. Nizet is an acting instructor in the Department of Pediatrics, Children s Hospital, Seattle, Washington. Dr. Nizet obtained his M.D. in 1989 from Stanford University. Dr. Craig Rubens will act as mentor. Dr. Rubens is Associate Professor of Pediatrics. He obtained a Ph.D. in microbiology from the Medical University of South Carolina in 1978 and M.D. from the University of Washington in 1982. Dr. Nizet will examine the role of beta hemolysin in group B streptococcal infections and its ability to cause cellular damage in the lung. His studies will focus on the identification of the genes involved in the regulation and structure of this lysin, and in vitro and in vivo pathogenesis studies using group B streptococci with knock-outs in these genes. The proposed studies are based on successful preliminary studies in which Dr. Nizet has made TN916, TN917, and chemical mutagenesis mutants that resulted in elevated and diminished levels of hemolysin. He has also prepared site directed mutants in group B streptococci to test the possibility that a known group B hemolysin might be the major group B hemolysin. He found that it was not. His "training plan" appears to primarily constitute protection of 85% of this time for research training. He proposes to develop molecular, genetic, and pathogenesis skills required for his studies. In particular he will learn techniques involved in cloning and sequencing DNA, preparing knock out mutants, conducting rigorous evaluation of the validity of molecular and genetic techniques, and applying them to in vitro and in vivo models of infection.